1. Field of the Invention
The present invention relates generally to filament dispensing apparatus for use on a missile or other airborne vehicle to establish a data link, and, more particularly, to such filament dispensing apparatus which rotates during use about an axis generally transversely of the direction of filament dispensing.
2. Description of Related Art
There are many present day weapon systems which include a launched missile having a wire or optical fiber data link, one end of which is connected to on-board control apparatus and the other end of which pays out at a high rate of speed during use to maintain interconnection with further control apparatus at the launch site.
There are a number of criteria which must be met by such apparatus in order to successfully act as a missile data link. First of all, filament payout has to be accomplished with a minimum of tension on the filament to avoid breakage, or in the case of an optical fiber, to prevent micro-bending which has been found to reduce the quality and efficiency of signal transmission. Secondly, the filament winding package should be stable so as to enable storage without having the winding collapse from its wound configuration. Thirdly, the winding should be dense and compact, taking as little space as is absolutely necessary.
A common type of present day filament dispenser consists of a generally cylindrical canister that is fixedly located at the aft end of the missile and onto which the filament is wound to achieve a tapered outside payout arrangement. A second form consists of a cylindrical canister in which the filament is wound so as to be able to effect payout from the inside of the filament package, the latter being especially utilized for torpedo and sonobuoy applications.
The outside payout canister approach suffers from poor space utilization due to the taper winding pack and layer-to-layer stepbacks which are typically used. On the other hand, inside payout overcomes the volumeteric efficiency penalty of the outside payout apparatus, but has yet to achieve the relatively high payout speeds required for missile applications. Also, the adhesive which is required to stabilize the filament windings, in both the inside and outside payout versions, causes severe bending of the cable at the peel point which induces high stress and concomitant optical signal loss. Still further, the incorporation of adhesive into the winding process adds significantly to production costs and contributes to optical loss of the wound fiber.
An even more difficult problem encountered with both of the noted prior art dispensing apparatus are that the filament on being withdrawn from an axially mounted fixed dispenser experiences a whirling motion imposing a requirement that the dispenser be mounted at the aft end of the vehicle, that it be mounted free from obstructions or that means be provided for damping the helix formed by the dispensed filament.